By Frank D. Roylance , SUN REPORTER|August 15, 2008
It was billed as a debate over the 2006 decision by the International Astronomical Union that kicked Pluto out of the family of planets, leaving just eight.
But in the end, after a jocular and noisy tussle before scientists and educators gathered at the Johns Hopkins University's Applied Physics Laboratory, both debaters agreed that the IAU's definition only muddied the waters, and that more time is needed for science to sort out the increasingly complex range of objects circling our sun and other stars.
"Get the notion of counting things out of your system," said Neil deGrasse Tyson, director of New York's Hayden Planetarium. "The more we learn about anything, the more we have to tune the vocabulary we use to describe it."
The two debaters also expressed delight that a scientific debate has captured so much public attention.
"How many scientists get to have their business in the op-ed pages, in comic strips?" said Tyson.
Mark Sykes, director of the Planetary Science Institute in Tucson, Ariz., agreed that it's not how many planets we count that's important.
"It's that debate, that exposure of issues to people that's more important," he said. "This is helping to expose a little bit more of the messy side of science, this clash of ideas ... and it's a good, positive thing."
Tyson and Sykes faced off before scientists and educators gathered to discuss the IAU's definition of planets to the exclusion of Pluto.
Tyson, an astrophysicist, is OK with Pluto's reclassification as a "dwarf planet" or "plutoid." In his view, the word planet desperately needed a new definition that reflects all that's been learned about the solar system since the ancients first noticed that planets behaved differently than stars.
Pluto has been revealed to be different from the eight other planets. "The time has come to discard the useless words and reinvent an entire system to respect the level of science we have achieved," he argued.
Sykes found the IAU's new definition confusing and disruptive. He argues that anything orbiting the sun that's large enough that gravity has pulled it into a near-spherical shape - including Pluto - should be classed as a planet.
"We're interested in which objects exhibit similar characteristics, so that when we send spacecraft out into the solar system ... we can understand these things better," he said. The IAU's definition won't even work on the planets found circling other stars.
